hi
i have a drill from NSI, they have many different drill bits but the only ones i use are for the free edge to back fill, they have a two week fill and a four week fill bit, this is the size of the drill bit head and indicated the amount of growth that will need replacing so u only need to drill one line ( let heat and friction on the nail and client), also i use a very narrow pointed drill bit to smooth out the back/ underneath of the nail ( the bit where your own nail joints with the enhancement), this cleans the underside and also stops clients from picking if there is a slight ridge. HTH